The right answer depends on how it was installed in the first place; on an RPM-based system, running "rpm -e j2sdk-1.4.2" might be the right thing; on another system, there may be a different package manager, and you may need to use that. On still other systems, the JDK may have been installed using Sun's default installer, which basically just dumps the files wherever you ask it to (often something like /usr/java/j2sdk1.4.2) and a simple "rm -rf" works great. But without knowing more about the system, we can't really tell you what to do.